The skeletal dysplasias are a heterogeneous group of disorders which result in disproportionate short stature and/or skeletal deformities. This study involves a multidisciplinary investigation of the clinical, genetic, morphologic, biochemical and molecular characteristics of the skeletal dysplasias. The limb lengthening protocol is designed to assess the medical and psychological benefits of experimental limb-lengthening procedures to increase height in individuals with severe short stature. In the future the GCRC will continue to assist in the evaluation of patients undergoing these procedures.